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Formicapyridine-type racemates, streptovertidines A (1) and B (2), a 7,24-seco-fasamycin, streptovertidione (3), and the fasamycin-type streptovertimycins I-T (4-15), together with 13 known fasamycin congeners (16-28), were isolated from soil-derived Streptomyces morookaense SC1169. Their structures were elucidated by extensive spectroscopic analysis and theoretical computations of ECD spectra. The fasamycin-type compounds 5, 8-12, 14, and 15 exhibited activity against the drug-resistant bacteria MRSA and VRE (MIC: 1.25-10.0 μg/mL). All isolates, except 3, 4, 10, and 24, displayed cytotoxicity against at least one of the human carcinoma A549, HeLa, HepG2, and MCF-7 cells (IC50 < 10.0 μM), of which some were also cytotoxic to the noncancerous Vero cells. Taken together, the activity data demonstrated that the fasamycin-type compounds were more selective to the tested bacteria over the mammalian cells. Structure-activity relationship analysis suggested that chlorination at C-2 in antibacterial fasamycin-type compounds improves the activity and selectivity to the bacteria. Theoretical simulations of reaction paths and chemical reactions for conversion of 3 to 1 were carried out and supported that the pyridine ring formation in formicapyridines proceeds nonenzymatically via 1,5-dicarbonyl condensation with ammonia.

Five new pentacyclic triterpenoids, 6α-hydroxyursolic acid (1), 6α-hydroxycorosolic acid (2), 6-oxo-maslinic acid (3), 6-oxo-δ-maslinic acid (4), and 6-oxo-alphitolic acid (5), along with 15 known analogues were isolated from the leaves of Cleistocalyx conspersipunctatus. Their structures were elucidated by spectroscopic analysis. Compound 1 displayed better α-glucosidase inhibitory activity (IC50: 2.6 μM) than the known inhibitor corosolic acid (IC50: 15.5 μM). Structure–activity relationships in the activity were discussed for this group of isolates.

Six previously undescribed cytochalasans, ueckerchalasins A-E and 4'-hydroxycytochalasin J

Eight new diarylheptanoids, coriandralpinins A–H (1–8), were isolated from the rhizomes of Alpinia coriandriodora, an edible plant of the ginger family. Their structures, including the absolute configurations, were established by extensive spectroscopic analysis and ECD calculations. Compounds 1–8 have a 1,5-O-bridged diarylheptanoid structure featuring polyoxygenated aryl units. When evaluated for intracellular antioxidant activity using t-BHP stressed RAW264.7 macrophages, all these compounds scavenged reactive oxygen species (ROS) in a concentration-dependent manner. Compounds 3 and 5 also showed inhibitory activity against NO release in LPS-induced RAW 264.7 cells. Six known flavonols, 7,4′-di-O-methylkaempferol, 7-O-methylquercetin, 7,4′-di-O-methylquercetin, 7,3′,4′-tri-O- methylquercetin, kaempferol 3-O-β-d-(6-O-α-l-rhamnopyranosyl)glucopyranoside, and 3-O-β-d-glucopyranuronosylquercetin were also isolated and characterized from the rhizomes.

Eight new polyhydroxanthones, penicixanthones A–H (1–8), including four monomers (1–4) and four dimers (5–8), were isolated from solid cultures of Penicillium purpurogenum SC0070. Their structures ...

The one-stage partial nitritation–anammox (PN–A) process is considered an efficient process for low-cost nitrogen removal. In this study, the nitrogen removal performance of different-sized granules in a one-stage PN–A reactor was studied. The total autotrophic nitrogen removal rate (TANRR) of the granular sludge increased as the granule size increased, and the TANRR of granular sludge with a radius larger than 500 μm reached 0.14 kgN kgVSS−1 d−1. High-throughput sequencing revealed that the abundance of ammonium-oxidizing bacteria and anaerobic ammonium‐oxidizing (anammox) bacteria in granular sludge of different sizes differed, indicating that the bacterial community structure was affected by the granule size. The TANRR of different-sized granules was affected by the volumes of aerobic micro-zone and anaerobic micro-zone inside the granule. Appropriate micro-zone volumes inside the granules could be regulated by the dissolved oxygen (DO) concentration of the reactor, which are favourable for achieving a balance between partial nitritation and anammox and then satisfactory nitrogen removal. Small-volume variations in the range of micro-zones have a significant influence on the balance between partial nitritation and anammox. The proper DO concentration required for different-sized granules to achieve better nitrogen removal differed. This study provides a novel perspective for understanding the effect of micro-zones of granular sludge on one-stage PN–A nitrogen removal.

Two new 2H-pyranones (1 and 2), two new isocoumarins (4 and 5), and two known compounds (3 and 6) were obtained from solid cultures of the endophytic fungus Pestalotiopsis microspora SC3082. Their ...

Eight new fasamycin-type polyketides, streptovertimycins A–H (1−8), were isolated from soil-derived Streptomyces morookaense SC1169 cultivated on wheat grains. Their structures were established by extensive spectroscopic analysis and theoretical computations of ECD spectra. Compounds 1−8 have a fasamycin-type pentacyclic structure featuring a 15-O-methyl group. They exhibited potent activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) with MIC values in the range of 0.63–5.0 μg/ml. The activity profile provided new insights into the structure–activity relationships of fasamycin-type antibiotics.

Four new pestalone-type benzophenones, pestalotinones A-D (1-4), along with six known congeners, pestalone, pestalone E-F, SB87-Cl, SB87-H, and pestalachloride B, were isolated from the endophytic fungus Pestalotiopsis trachicarpicola SC-J551 cultivated on rice grains. Their structures were established by extensive spectroscopic analysis. Compounds 1-3 exhibited potent activity against Staphylococcus aureus and MRSA (MIC: 1.25-2.5 μg ml

Formicapyridine-type racemates, streptovertidines A (

Two new bisabolane-type sesquiterpenoids, (3R,4S,5R,7S)-3,4,5-trihydroxybisabola-10-ene-9-one (1), (1R,2S,5R,7R,8S)-2,8-epoxy-5-hydroxybisabola-3,10-diene-9-one (2), together with seven known anologues (3–9), were isolated from the cooking liquid of Curcuma longa rhizomes. Their structures were elucidated by a combination of 1D and 2D NMR spectroscopic and HRESIMS data. The absolute configurations of compounds 1 and 2 were assigned by electronic circular dichroism (ECD) calculations. Compound 2 exhibited in vitro anti-inflammatory activity with an IC50 value of 25.5 ± 3.1 μM comparable to that of the positive control.

Different microbial aggregates show substantial differences in morphology, and extracellular polymer substances have been confirmed to play a key role in the formation of aggregates. In this study, three different microbial aggregates and their exopolysaccharides were compared. The results show that the granular sludge was largest in size and the most compact in shape. Biofilms with a certain thickness had the next greatest density, and flocculent sludge, with the smallest particle size, was the loosest. The extended Derjaguin-Landau-Verwey-Overbeek analysis shows that hydrogen bonding, hydrophobic and electrostatic interactions affect the aggregation of microorganisms. A comparison of exopolysaccharides shows that granular sludge exopolysaccharides show the highest hydrophobicity (38.08%) and lowest surface charge (−20.5 mV), followed by biofilm exopolysaccharides (27.9% and −24.8 mV respectively). The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy show that the contents of hydrophilic and hydrophobic functional groups and charged functional groups of exopolysaccharides affect the above properties of exopolysaccharides, thereby affecting microbial aggregation. In addition, the hydrogen bond content of exopolysaccharides in granular sludge (19.3%), biofilm (19.2%) and activated sludge (18.9%) decreased sequentially. This also affects the cross-linking of microbial exopolysaccharides to form hydrogels. Finally, the results of confocal laser scanning microscopy showed that, different from the other two aggregates, the extracellular α-polysaccharides of granular sludge are mainly distributed in the nucleus, which is more conducive to aggregation. The research results of this thesis provide a new understanding of the differences in the aggregation morphology of different aggregates from the perspective of exopolysaccharides.

Eight new polyhydroxanthones, penicixanthones A-H (

Parabolic canals are commonly used in seasonally frozen regions because of their excellent hydraulic characteristics and frost heave resistance. However, severe frost damage can still occur, mainly because the design of canals is based on experience, and the analytical mechnical models and design methods are limited. First, the frost heave characteristics of parabolic canals were analysed, and the canal lining was simplified as an arched thin shell structure under the normal frost heave force, tangential freezing force, and gravity. Second, an analytical mechanical model of frost damage to the lining was established, and the equations for the axial force, bending moment, tensile stress were derived; the accuracy of the model was verified by field measurements and numerical simulations of a canal case. Third, the effects of groundwater depth and canal size were analysed, and the frost damage mechanism was investigated. Fourth, the anti-frost heave design method of a canal based on the hydraulic optimal solution set was proposed, and the method was encapsulated into digital design software with Python language. This mechanical model can explain the frost damage of the canal, and the nonuniform frost heave of foundation soil caused by different groundwater depths in different parts of the canal is the cause of lining damage. The bi-objective optimization design method can consider the hydraulic performance and anti-frost heave performance of the canal, and the digital design software can assist engineers with developing a quick and accurate design approach. The research results can provide a theoretical basis and technical means for cold-region canal design.

Four new cyclodepsipeptides, dinghupeptins A-D (1-4), possessing a rare N5-(2-hydroxylethyl)glutamine moiety, were isolated from cultures of the soil-derived Streptomyces sp. SC0581. Their structures were elucidated by spectroscopic and advanced Marfey's amino acid analysis, and their 3D structures were established by theoretical conformational analysis. Compounds 1 and 2, containing a 3-amino-6-hydroxypiperidone unit, displayed selective inhibition of chymotrypsin with IC50 values of 2.1 and 1.1 μM, respectively. Enzyme kinetic analysis and molecular docking experiments revealed they are competitive inhibitors binding to the active site of chymotrypsin.

Four new peptaibiotics, acremotins A–D (1–4) featuring three α,α-dialkylated amino acid–imino acid motifs and an unreduced C-terminal residue, along with the known peptaibiotic XR586 (5) were isolated from the solid cultures of the soil-derived fungus Acremonium persicinum SC0105. Their primary structures were characterized by detailed analysis of the HRESIMS/MS fragmentation pattern combined with comprehensive interpretation of the 1D and 2D NMR spectroscopic data. The absolute configurations of amino acid residues were determined by the advanced Marfey’s method. Sequence alignment result shows that 1–4 are closely related to zervamicin IIB and emerimicin IIA, thus belong to peptaibiotic subfamily-3 (SF3). The three-dimensional (3D) structure of 4 was established by theoretical conformational analysis using the ab initio density functional theory (DFT) method, which, together with the CD spectrum, indicated an amphiphilic and helical structure for 4. 1–5 actively inhibited the growth of gram-positive bacterial pathogens, and amongst them 4 was the most potent compound showing MIC of 12.5 and 6.25 µg/ml against S. aureu and MRSA strains, respectively. 1–5 were also cytotoxic against three human cancer cell lines with IC50 ranging from 1.2 to 21.6 μM.

Ice flashover of insulators seriously affects the safe operation of transmission lines. Flashover path of ice-covered insulators is one of the key influence factors. Due to the randomness and complexity, the existing researches lack the systematic and in-depth study on the flashover path of ice-covered insulators. In this paper, a large number of flashover tests of ice-covered insulators are carried out in the natural field. The flashover paths are classified by its characteristics as transverse bridging arc and longitudinal bridging arc, which are analyzed by probability statistics. The effects of icing degree and string length on various types of arc are analyzed. In addition, the leakage distance utilization ratio is defined to analyze the influence of flashover path on flashover voltage. The results show that as the icing degree becomes heavier, the probability of longitudinal bridging arc gradually increases, while transverse bridging arc gradually decreases. The influence of string length on arc type is related to the icing degree. Under mild icing condition, the probability of longitudinal bridging arc and transverse bridging arc has nothing to do with string length, but under moderate icing condition, with the increase of string length, the probability of transverse bridging arc increases significantly. Moreover, it is also found that the effect of flashover path on the leakage distance utilization ratio is one of the reasons that leads to the non-linearity of flashover voltage of long ice-covered insulators.

Two new diketopiperazines, cyclo( l -Phe- l -NMe-DOPA) (2) and cyclo[ l -Phe- l -(NMe-3-(NMe-3-O-α- l -rhamnopyranosyl)-DOPA] (3), along with a known diketopiperazine (1), were isolated from the cultures of Streptomyces sp. SC0581. Their structures were elucidated by extensive spectroscopic analysis, single-crystal X-ray crystallographic analysis, and chemical correlation. Compounds 1 − 3 exhibited more potent ABTS radical cation scavenging activity (IC50 values: 3.7 − 14.6 μM) than l -ascorbic acid (IC50: 17.7 μM). Compounds 2 and 3 also showed remarkable DPPH radical scavenging activity.

Seven new dimeric tryptophol-related alkaloids (1-4, 5a, 5b, and 6) were isolated from solid cultures of the endophytic fungus Colletotrichum sp. SC1355. The structures and absolute configurations of these compounds were determined by NMR spectroscopic analyses in combination with quantum chemical calculations of NMR (GIAO) shifts and ECD spectra. This is the first report of fungus-derived tryptophol dimers. In addition, the isolated compounds were evaluated for acetylcholinesterase (AchE) inhibitory activity.

Parapapillary atrophy (PPA) is a kind of atrophic abnormality of eyes, which lies on the retinal fundus adjacent to optic disc (OD). Clinically, PPA is correlated with several pathologies of eyes. For example, the area of PPA has a strong association with the severity of myopia. In this work, we developed a new segmentation algorithm aimed at PPA in retinal images. The frame work was derived from Holistically-Nested Edge Detection (HED), which originally deals with edge detection. Firstly, extracting region of interest (ROI) and normalizing datasets were performed in preprocessing stage. Next, an end-to-end model began to acquire rich hierarchical features with deep supervision on side outputs. We applied a new balance parameter to loss function for realization of the area segmentation. Finally, the holistic image predictions (PPA area segmented) were performed through full convolutional neural layers. The model training on retinal images with annotation from professional ophthalmologist achieves great performance on both adults and pupils datasets. Experiential results present the average F-score of 0.7910 on adults' test data (200 images) and 0.7478 on pupils' (50 images). MIoU of the segmentation reaches 0.7237 of adults and 0.6892 of pupils.

Parapapillary atrophy (PPA) is a crescent atrophic abnormality adjacent to optic disk (OD). In clinical findings, PPA is highly related to glaucoma and high myopia, which makes it a potential indicator for ophthalmic diseases. Therefore, it is significant to develop an algorithm for automatic segmentation of PPA so as to aid the treatment and the prevention of eye diseases. A method that combines the confidence map with conditional random field (CRF) model is proposed in this paper to achieve the optimization of initial segmentation results from neural network. Holistically-Nested Edge Detection (HED) is applied to the segmentation of PPA and a confidence map is obtained. The CRF model is constructed with the confidence map and Maximum a posteriori (MAP) inference is implemented to conduct the segmentation. Post-processing is utilized to further refine the segmentation result. The proposed method has the advantage of robust performance when there is difference between training set and test set. The experimental results show that the average F-score is increased from 0.57 to 0.67, which shows a fair improvement effect.

Numerical models for a new generation of hip prosthesis were established because models of replacements with a pelvis are not described in the literature. The stress and strain distribution in the bone and prosthesis were studied by numerical simulation and the results validated experimentally. Numerical simulation was also used to study the outcome when placing the same hip joint into bone of different densities. The results showed that the numerical simulations of hip models with a pelvis were more consistent with a physical model. The mechanical parameters of bone density could significantly affect the stress and strain distribution of the bone and prosthesis.

Background and objective To develop an automatic parapapillary atrophy (PPA) detection algorithm in retinal fundus images and discuss the association between PPA and myopia to facilitate diagnosis and prediction of children myopia. Methods The proposed algorithm consists of PPA identification and segmentation, which are evaluated by comparing with ophthalmologist's annotation. The association between PPA parameters and myopia is analyzed via Spearman correlation. Results The accuracy of PPA identification reaches 90.78%. The F1-score of PPA segmentation is 0.67, and the Pearson correlation between the automatic measurement and ground truths for the area of PPA (APPA), the ratio (μ) of APPA to the area of optic disc (OD) and the maximal width of PPA (W) are 0.74, 0.60, and 0.69 (all p Conclusions The proposed algorithm can provide accurate PPA measurement. Strong association between the changes of PPA and the progress of children myopia are observed and the width of PPA has the best association among three PPA parameters.

This paper introduces the simulation of the MOSFET common-source amplifier circuit, and provides a method to jointly solve the physical model of the device and the external circuit to simulate the transient electro-thermal characteristics of a single device in the actual operation of the circuit. The spectral element time-domain (SETD) method is used to solve the coupling drift-diffusion model equation by using the electronic quasi-fee potential, the hole quasi-Fei potential and the potential as variables. The corresponding current density and electrical strength distributed in the device can be used to couple the heat transfer equation. Furthermore, the Kirchhoff laws should be satisfied when the MOSFET device is inserted in the circuit. The numerical results demonstrate the validity of the proposed method.